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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

38258 results found.

  1. GRB 240814C: Fermi GBM Final Real-time Localization
  2. Fermi GRB 240814B: Global MASTER-Net observations report
  3. GRB 240812B: SVOM/GRM observation
  4. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  5. GRB 240814B: Fermi GBM Final Real-time Localization
  6. GRB 240814A: Fermi GBM Final Real-time Localization
  7. Fermi trigger No 745220784: Global MASTER-Net observations report
  8. Konus-Wind detection of GRB 240811A
  9. Konus-Wind detection of GRB 240810A
  10. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  11. GRB 240809A: Correction to the VLA source position in GCN 37158
  12. GRB 240810A: SVOM/GRM observation
  13. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  14. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  15. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  16. GRB 240809A: ATA radio non-detection
  17. GRB 240812D: Fermi GBM Final Real-time Localization
  18. GRB 240812C: Fermi GBM Final Real-time Localization
  19. GRB 240809A : RAPAS follow-up observations
  20. GRB 240809A: VLA detection
  21. GRB 240809A: ALMA detection
  22. IPN triangulation of GRB 240810A (short)
  23. GRB 240811A: Swift-BAT refined analysis
  24. GRB 240809A: Swift-BAT refined analysis
  25. EP240807a: PRIME H-band upper limits
  26. GRB 240812B: AstroSat CZTI detection of a long burst
  27. GRB 240811A: Bassano Bresciano Observatory upper limit
  28. GRB 240811A: Swift-XRT refined Analysis
  29. Fermi Gamma-ray Burst Monitor trigger 745135620/240812255 is not a GRB
  30. GRB 240811A: Swift/UVOT Upper Limits
  31. EP240801a: Assy-Turgen optical observations
  32. Fermi GRB 240810A: Global MASTER-Net observations report
  33. Fermi Gamma-ray Burst Monitor trigger 240812094/745121685 is not a GRB
  34. GRB 240812A: Fermi GBM Final Real-time Localization
  35. GRB 240811A: LCOGT Optical Upper Limit
  36. GRB 240811A: Enhanced Swift-XRT position
  37. GRB 240811A: Upper limits with Mephisto
  38. Konus-Wind detection of GRB 240809A
  39. Fermi trigger No 745057312: Global MASTER-Net observations report
  40. Swift GRB 240811A: Global MASTER-Net observations report
  41. GRB 240811A: Swift detection of a burst
  42. Fermi Gamma-ray Burst Monitor trigger 745050426/240811269 is not a GRB
  43. GRB 240810A: Fermi GBM Final Real-time Localization
  44. GRB 240809A: REM detection of the optical afterglow
  45. GRB 240809A: Bassano Bresciano Observatory optical observations
  46. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  47. GRB 240809A: Conclusive redshift from VLT
  48. Fermi-LAT gamma-ray observations of IceCube-240808A
  49. GRB 240809A: KAIT optical observations
  50. GRB 240808A: AstroSat CZTI detection
  51. GRB 240809A: GIT afterglow observations
  52. GRB 240809B: MAXI/GSC detection
  53. GRB 240809A: Swift/UVOT Detection
  54. GRB 240809A: Tentative redshift from NOT
  55. GRB 240809A: Swift-XRT refined Analysis
  56. IPN triangulation of GRB 240807A / EP 240807a
  57. X-ray Transient EP240807a: PRIME near-infrared upper limits
  58. Swift GRB 240809A: Global MASTER-Net observations report
  59. GRB 240809A: JinShan optical observations
  60. GRB 240809A: Enhanced Swift-XRT position
  61. GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
  62. GRB 240809A: SVOM/GRM observation
  63. GRB 240808A: SVOM/GRM observation
  64. GRB 240807A: SVOM/GRM observation
  65. GRB 240809A: Swift detection of a burst with a bright optical counterpart
  66. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  67. GRB 240807B: AstroSat CZTI detection of a short burst
  68. IceCube Alert 240808.27: Global MASTER-Net observations report
  69. EP EP240807a: Global MASTER-Net observations report
  70. EP EP240806a: Global MASTER-Net observations report
  71. GRB 240801A: GRBAlpha detection
  72. GRB 240807B: Fermi GBM Final Localization
  73. GRB 240710B: VZLUSAT-2 detection
  74. GRB 240805A: ATCA Radio Upper Limits
  75. Fermi trigger No 744761058: Global MASTER-Net observations report
  76. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  77. EP-WXT trigger 01709018832: KAIT optical observations of the star flare
  78. EP240802a/GRB240802A: KAIT optical upper limit
  79. GRB 240720B: VZLUSAT-2 detection
  80. GRB 240710A: VZLUSAT-2 detection
  81. GRB 240807A: Fermi GBM Final Localization
  82. EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
  83. GRB 240805B: GIT optical upper limit
  84. EP240806a: KAIT optical observations
  85. GRB 240805B: Swift-BAT refined analysis
  86. GRB 240805A: Swift-BAT refined analysis
  87. Fermi trigger No 744629911: Global MASTER-Net observations report
  88. EP240804a (GRB 240804B): NOT optical observations
  89. EP240806a: LCOGT optical counterpart detection
  90. Konus-Wind detection of GRB 240802A (EP240802a)
  91. Improved IPN triangulation of GRB 240802A / EP 240802a
  92. Konus-Wind detection of GRB 240805A
  93. GRB 240805B Bassano Bresciano Observatory upper limit
  94. GRB240805A: Fermi GBM Observation
  95. GRB 240805B: JinShan optical afterglow detection
  96. GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
  97. GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
  98. Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
  99. Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
  100. GRB 240626B: VZLUSAT-2 detection

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